My son is hoping to buy his first house, and to move into it with his girlfriend. They split up for a few weeks last summer but are back together now and seem happy. The reason I mention that is because I have advised him not to get into a shared mortgage with someone if there's any prospect of their relationship not lasting, as it complicates things. He earns quite a lot more than her, but is stretching himself financially to get the mortgage he needs to pay for the right house which he views as a longterm investment. I asked him if she was going to pay rent and he said he thought she'd just say, if she has to pay rent then she might just as well put herself on the mortgage and buy the house with him. Is it unreasonable to expect her to pay her own way? She is currently paying monthly rent, same as him, at the house they live at. I don't think she should be expecting to pay nothing and effectively to live for free. Does anyone have experience of this situation with their own children? TIA.